ROTOR ASSEMBLY FOR AN ELECTRIC MACHINE

The present disclosure relates to a rotor assembly (10) for an electric machine (1). The rotor assembly (10) comprises a rotating shaft (20), a rotor (30) and a fluid cooling system. The rotor (30) is fixed to the rotating shaft (20). The rotor (30) comprises a rotor core (32), a first end plate (34) and a second end plate (36). The first end plate (34) is provided at a first axial end (32a) of the rotor core (32). The second end plate (36) is provided at a second axial end (32b) of the rotor core (32). The fluid cooling system (100) comprises at least one fluid cooling pathway (110) provided internally in the rotor (30). The at least one fluid cooling pathway (110) is configured to guide cooling fluid through the rotor (30), and comprises at least one cooling channel (124, 126) and a downstream end plate channel (125, 128).The at least one cooling channel (124, 126) extends through the rotor core (32) from the first axial end (32a) to the second axial end (32b). The downstream end plate channel (125, 128) is fluidically connected to a downstream end of the at least one cooling channel (124, 126). The downstream end plate channel (125, 128) is restricted radially outwards by a radially outer wall portion (125a, 128a). The at least one cooling channel (124, 126) is restricted radially inwards by a radially inner wall portion (124a, 126a). A radially innermost position (125b, 128b) of the radially outer wall portion (125a, 128a) is arranged in a range about or at or radially inwards of a radially innermost position (124b, 126b) of a radially inner wall portion (124a, 126a).